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Herpes Simplex Virus or Cold Sores

What are cold sores?

Cold sores are small blisters around the mouth, caused by the herpes simplex virus. They are sometimes called "fever blisters." The most common strain of the virus that causes cold sores is herpes simplex virus 1.

Once infected, the herpes simplex virus becomes dormant (inactive) for long periods of time and may reactivate, during which time cold sores reappear. Episodes of the cold sores usually do not last longer than 2 weeks. Hot sun, cold wind, a cold, or a depressed immune system can cause a reactivation of herpes simplex virus symptoms.

The herpes simplex viruses in the cold sores are contagious, and can be spread to others by kissing, sharing cups or utensils, sharing wash cloths or towels, or by direct touching of the cold sore before it is healed. The virus can also be spread to others in the day or so just before the cold sore appears. 

What are the symptoms of cold sores?

Some children and adults never experience any symptoms with the first attack; others have severe flu-like symptoms and ulcers in and around the mouth. Recurrences of cold sores are usually not as severe as the original outbreak. These are the most common symptoms of cold sores:

  • A small blister or cluster of blisters on the lips and mouth that enlarge, burst, then crust over

  • Tingling, itching, and irritation of the lips and mouth

  • Soreness of the lips and mouth that may last from three to seven days

The symptoms of cold sores may look like other skin conditions or medical problems. Always see your child's healthcare provider for a diagnosis.

What is the treatment for cold sores?

Although the herpes simplex virus infection that causes cold sores cannot be cured, treatment may help relieve some cold sore symptoms, if severe. Treatment may include antiviral medicine and other types of prescription medicines. These medicines work best if started as soon as possible after the first sign of a herpes infection or recurrence. Always see your child's healthcare provider.

Medical Reviewers:

  • Freeborn, Donna, PhD, CNM, FNP
  • Lentnek, Arnold, MD